This invention relates to utilization of discarded solid soap materials, such as retrieved from hotels or motels or any other source of discarded soap and the like, to obtain free fatty acids for other fields of use.
It has been proposed by Gueant et al. (U.S. Pat. No. 4,018,805) to convert soaps to corresponding fatty acids by treating a mixture of molten soaps and a diluent fatty acid mixture with a relatively dilute solution of a mineral acid and to separate fatty acid from a solution of mineral salt formed during the reaction.
Red et al. have proposed, in U.S. Pat. No. 4,118,407, a process for recovery of fatty acids from soap stocks, in which saponified soapstock is acidulated with an inorganic acid and the products separated. It has further been proposed that a relatively dilute aqueous solution of mineral salts, resulting from the reaction, be concentrated and used in paper processing, to dispose of an otherwise unacceptable effluent material in an economically and ecologically acceptable manner.
Recovery of soaps, or corresponding fatty acids, from soapy solutions of the kind obtained in waste liquors from soap manufacturing plants or laundries has been considered by Gibbs (U.S. Pat. No. 2,637,727), Peck (U.S. Pat. No. 1,349,530) and Gray (U.S. Pat. No. 1,242,435). In each case a relatively dilute material is treated to permit recovery of soap or fatty acid and to decrease an effluent problem. However, it is well known that handling large volumes of soapy effluents is inefficient and is accompanied by problems in handling emulsions and frothy materials.
Recovery and refining of fatty acids from soap stocks, within the context of saponification of commercially-used fats and oils, is addressed by Cox et al. (U.S. Pat. No. 2,812,343). Wengrow et al. (U.S. Pat. No. 3,804,819) and Phillips et al. (U.S. Pat. No. 4,100,181). These processes generally require saponification, acidulation and one or more extraction steps. Akers et al. have proposed in U.S. Pat. No. 4,259,251, treating effluent containing fatty matter by extraction with a non-polar solvent to concentrate fatty matter and saponification of the fatty matter to produce fatty acid soaps.
Recovery of fatty acids from liquid laundry wastes containing the same has been proposed by Urbain et al. in U.S. Pat. Nos. 2,171,198; 2,171,200; 2,171,201 and 2,171,202. The proposed procedures provide for handling dilute soap solutions and involve one or more filtration or decolorization steps, along with treatment with dilute acid.
Although it is conventional in the hospitality industry to provide one or more cakes of soap to each guest in a motel, hotel or inn, no procedure is currently employed to recover unused soap or to obtain any useful products therefrom. On the contrary, soap remnants are given to custodial personnel or discarded in the trash. Similarly, partially used soap cakes dispensed to patients in hospitals and nursing homes are discarded or incinerated. There is therefore a need for a method of recovering, economically, useful materials from soap materials heretofore discarded in the hotel industry.